The polyamine metabolism of the rat mammary Gland will be studied during the process of mammary carcinogenesis. The effect of dimethylbenz(a)anthracene on the levels of polyamine acetokinase, ornithine decarboxylase, S-adenosylmethionine decarboxylase and spermidine synthetase in the mammary gland will be studied. The enzyme levels will also be studied in the rat tumors after ovariectomy and after treatment with estradiol-17 beta. Tissue levels of putrescine, spermidine, spermine, and the acetylated derivative of these compounds will also be studied.